The biological and behavorial patterns of the various species of shark have been studied and reported in the literature. One such book entitled "Sharks, Skates, and Rays" edited by Perry W. Gilbert, and published in The John Hopkins Press, Baltimore, Maryland, presents and discusses in a highly scientific manner the 39 papers presented in the interdisciplinary symposium entitled "Current Investigations Dealing with Elasmobranch Biology" convened at the Lerner Marine Lab, Bimini, Bahamas, in January/February 1966. Other books such as "Cousteau", published by Doubleday, present the shark, its detection, and its repulsion in a layman's language. Many other publications such as "The Electric Sense of Sharks and Rays", by Ad Kalmijn, Journal of Exper. Biology, Vol. 55, Issue 2, October 1971 pages 371-385; and "The Vision of Sharks: a Perspective" by Samuel H. Gruber in Vol. XXX, No. 2, of the Department of Navy publication "Review" are of academic interest. Also noted are the references cited in the Gruber publication.
The aforementioned prior art purports "to stimulate the nervous system of sharks with electro-magnetic radiation" in that, "obviously the repelling or killing is not in the form of electrical shock xxx". The prior art, Hicks U.S. Pat. No. 3,164,772 further notes that, "direct current (non-interrupted) as well as alternating current", has no effect whatsoever on the sharks. The reference does not suggest that an electric field has an effect. As best can be understood these prior art systems are attempting to "propagate" in sea water on-off electrically current via an "antenna".
Initially, and avoiding the technical terminology normally associated with the propagation of radio waves, the prior art prevents the electric field from being sustained into the surrounding medium. Theoretically, there would be an electric field (current flow between two electrodes) immersed in a conductive medium if sufficient power were to be applied. This may require enormous power, nonetheless theoretically feasible. The large current flow in turn requires an electric field. Alternatively, the prior art seems to have stumbled on an alternative source of enormous power, i.e., the brute force of the surge of a discharging capacitor.
Specifically, it is advanced that a continous d.c. current (as measured at the power supply) will not affect a shark is attributed to the effects of ionic conductivity in a media having ions and electrons with differing mobilities. That is, a space charge region rapidly forms in the vicinity of the anode and/or the cathode structures that prevent the electric field from penetrating the conducting medium. Specifically, the pulse rates and pulse duration of the prior art have not been directed to coincide with measured brain wave frequencies (6-12 cps in sharks) and nerve cell response times (0.5 to 10 milliseconds in most living organisms).